South: Cereal herbicides and oilseed rape a priority

Over thelast seven days we have had a phenomenal amount of rain. Last week Tuesdaythere was 3.5cm leaving the heavier ground impassable.

Onthe plus side all the crops are now evenly emerged and making rapid growth inthe mild weather. Slug numbers are diminishing on the treated fields. However,where no treatment has been carried out there are signs of severe grazing andthese fields should be carefully monitored. Under the present wet conditions Ifind that pellets bases on methiocarb such as Rivet give the best control.

Winterwheat crops are at the two to three leaf stage and clean. Winter barley cropsare at the three to four leaf stage and have signs of Net blotch andRhynchosporium, particularly on varieties Flagon and Casatta.

The problemis particularly worse on the min tilled fields where the infection has been pickedfrom the trash in the field. Usually it is not economic to spray barley in theautumn against disease as the cold frosty weather would normally control thediseases, but in the absence of frosts at present watch the disease progress.

The mildweather with no frosts so far means the crops are fairly soft. Don’t use anycomplicated herbicide tank mixes, especially those containing insecticides forfear of crop scorch. Some slight scorch is already evident, even where fairlysimple mixes have been used.

Rememberthat barley is more easily damaged than wheat and that some fields are carryingfoliar disease. Where blackgrass has emerged and is at two to three leaf stagethen Atlantis (mesosulfuron + iodosulfuron) should be planned in winter wheat.This is particularly important where no residual herbicide has been used.

Oilseedrape crops are growing very quickly and the biggest plants have eight to 10leaves. Untreated crops are now showing symptoms of Phoma and it would bepertinent to consider an application of a fungicide.

As thecrops are well advanced with GAI of nearly three it is worth considering aplant growth regulator fungicide based on metconazole or tebuconazole. Thefungicides can be tank-mixed with aphicides to control turnip yellow virus asthe seed dressings will be running out of steam in larger plants.

Look outfor blackgrass in oilseed rape crops where the graminicides or earlierresiduals may not have worked. Consider using Precis (propyzamide) oncetemperatures have dropped.